Stochastic suprasegmentals: relationship between the spectral characteristics of vowels, redundancy and prosodic structure

Previous work has shown a relationship between syllabic duration, redundancy within speech, and prosodic structure [1]. In addition, a spectral care of articulation measure of vowels in spontaneous speech has supported these duration results and suggest that care of articulation varies inversely with redundancy and conversely with prosodic prominence. However, these spectral measures remain inconclusive due to measurement difficulties. In this paper a simpler spectral measurement is presented as a metric of care of articulation and applied to three vowels from each corner of the vowel triangle. Prosodic and redundancy factors can predict up to 5% of the variance of this new measurement, supporting the inverse redundancy result. However, in contrast to syllabic duration, whether prosodic boundaries are controlled for or not, the predictive power of prosodic factors and redundancy factors remain relatively independent. This suggests that 1. phrase final syllables, despite lengthening, do not show increased care of articulation if measured spectrally, and 2. unlike duration, redundancy factors affect the spectral characteristics of vowels independently of prosodic structure.